Joe palka Posted December 20, 2017 Share Posted December 20, 2017 i have a 1989 RD688s believe it's the e7 with a 9 speed. the truck was idling and running around 190 - 195. after changing the thermostat and the water/coolant filter, it now idles at 180, but when running the truck both empty and loaded it makes its way back up just under 200. Another issue to screw things up is the red warning temp light above the gauge seems to go on at 150. then sometimes at 180. then on and off around 190. so it dosent stay too consistent. that light is all over the place. now with a temp gun the motor seems to be a few degrees cooler then the gauge which I'm sure could be normal. Im just debating on which route to go next as i chase this issue before the warm weather comes. But im looking to hear anyone's thoughts and maybe past experience. i appreciate any help. thanks. Quote Link to comment Share on other sites More sharing options...
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